The present invention is related in general to integrated circuits (ICs), and more particularly to an apparatus and method for providing data retention with reduced power consumption.
Many portable electronic devices such as cellular phones, digital cameras/camcorders, personal entertainment devices, laptop or palmtop computers, and video games operate on batteries. During periods of inactivity the device may not perform processing operations and may be placed in a power-down or standby power mode to conserve power. Power provided to ICs within the electronic device may be turned off in a standby power mode. Data retention circuits such as flip flops or latches within the device may be used to store status information for later use prior to the device entering the standby power mode. The data retention latch, which may also be referred to as a shadow latch or a balloon latch, is typically powered by a separate ‘always on’ power supply. However, presence of leakage current during the standby power mode represents a challenge for designing portable devices having an extended battery life.
Some data retention circuits may provide improved performance, some others may provide reduced silicon area, and few may provide a reduced leakage current. However, improvement in one parameter is often achieved at the cost of others, e.g., improvement in performance may be achieved at the cost of an undesirable increase in leakage current or silicon area or both, or an improvement in leakage current may make circuit inoperable or become less robust at lower voltages of a power source.